Activation of the thiazide-sensitive Na+-Cl- cotransporter by the WNK-regulated kinases SPAK and OSR1
Activation of the thiazide-sensitive Na+-Cl- cotransporter by the WNK-regulated kinases SPAK and OSR1
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DOI：
10.1242/jcs.025312
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发表时间：
2008-03-01
影响因子：
4
通讯作者：
Alessi, Dario R.
中科院分区：
文献类型：
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作者：
Richardson, Ciaran;Rafiqi, Fatema H.;Alessi, Dario R.
人类WNK 1激酶表达增加的突变导致假性醛固酮减少症II型高血压综合征。噻嗪类利尿剂可有效治疗这种疾病，其通过抑制Na+-Cl-协同转运蛋白（NCC）发挥作用，表明WNK 1和NCC之间存在联系。在这里，我们证明了由WNK 1激活的SPAK和OSR 1激酶在三个保守残基（Thr 46，Thr 55和Thr 60）磷酸化人NCC。通过用低渗低氯化物条件处理HEK 293或mpkDCT肾远曲小管衍生的细胞来激活WNK 1-SPAK/OSR 1信号传导通路，诱导NCC在被SPAK/OSR 1磷酸化的残基处磷酸化。NCC的有效磷酸化依赖于NCC中的RFXI基序与SPAK/OSR 1之间的对接相互作用。NCC中Thr 60突变为Ala显著抑制Thr 46和Thr 55的磷酸化以及低渗低氯处理诱导的HEK 293细胞NCC活化。我们的研究结果表明，WNK 1-SPAK/OSR 1信号通路在控制NCC的磷酸化和活性中起着关键作用。他们还提出了WNK 1过表达增加可导致高血压的机制，SPAK/OSR 1抑制剂可能通过抑制磷酸化从而抑制NCC活性来降低血压。
Mutations increasing WNK1 kinase expression in humans cause the pseudohypoaldosteronism type II hypertension syndrome. This condition is treated effectively by thiazide diuretics, which exert their effects by inhibiting the Na+-Cl- cotransporter (NCC), suggesting a link between WNK1 and NCC. Here, we demonstrate that the SPAK and OSR1 kinases that are activated by WNK1 phosphorylate human NCC at three conserved residues (Thr46, Thr55 and Thr60). Activation of the WNK1-SPAK/OSR1 signalling pathway by treatment of HEK293 or mpkDCT kidney distal-convoluted-tubule-derived cells with hypotonic low-chloride conditions induced phosphorylation of NCC at residues phosphorylated by SPAK/OSR1. Efficient phosphorylation of NCC was dependent upon a docking interaction between an RFXI motif in NCC and SPAK/OSR1. Mutation of Thr60 to Ala in NCC markedly inhibited phosphorylation of Thr46 and Thr55 as well as NCC activation induced by hypotonic low-chloride treatment of HEK293 cells. Our results establish that the WNK1-SPAK/OSR1 signalling pathway plays a key role in controlling the phosphorylation and activity of NCC. They also suggest a mechanism by which increased WNK1 overexpression could lead to hypertension and that inhibitors of SPAK/OSR1 might be of use in reducing blood pressure by suppressing phosphorylation and hence activity of NCC.